1. Technical Field
The invention relates to a lane departure detection and warning system for an automotive vehicle, and specifically to such a system providing a haptic warning of a lane departure condition.
2. Background Art
Automotive vehicles, such as passenger vehicles and heavy trucks, have been equipped with lane detection and lane departure warning systems. Such systems use a sensor, usually an optical sensor, which is able to detect lane markings or other road features ahead of the vehicle and determine a desired path of travel in a designated driving lane. In most such systems, a warning or alert is provided to the vehicle driver when the vehicle begins to depart from the desired driving lane. The warning or alert may be audible, visual, and/or haptic.
A haptic alert involves generating a vibration or “buzz” in a portion of the vehicle structure with which the driver is in contact, such as the steering wheel. To be effective, the haptic warning should be easily and intuitively discernible by the driver. If the vehicle is traveling over a rough or uneven road surface, the driver may feel road vibration or “noise” in the steering wheel that overpowers or masks the haptic warning. That is, the haptic warning may not be distinguishable from the road noise transmitted through the vehicle steering column and other components to the steering wheel. A haptic warning that is so strong or distinct that it serves as an unambiguous warning even in the presence of a large amount of road noise is likely to be unnecessarily strong and even annoying when driving on relatively smooth road surfaces.